JP2018177992A - Water-based coating, manufacturing method of substrate with coated film, and substrate with coated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-based coating capable of forming a coated film excellent in elongation under a low temperature condition, a manufacturing method of a substrate with a coated film having the coated film excellent in elongation under the low temperature condition, and the substrate with the coated film having the coated film on a surface.SOLUTION: There is provided a water-based coating containing a first polymer containing a unit based on fluoroolefin, a unit based on a monomer having no crosslinking group, and a unit based on a monomer having a crosslinking group, a second polymer selected from a group consisting of a fluorine-based polymer containing a unit based on vinylidene fluoride and a unit based on hexafluoropropylene, a fluorine-containing polymer containing a unit based on tetrafluoroethylene and a unit based on propylene, and a fluorine-based polymer containing a unit based on tetrafluoroethylene and a unit based on perfluoroalkylvinyl ether, an anionic surfactant, and water.SELECTED DRAWING: None

Description

  The present invention relates to a water-based paint, a method for producing a coated substrate, and a coated substrate.

A coating film formed of a fluorine-based paint containing a fluorine-containing polymer has excellent weather resistance, and is therefore attracting attention in the field of high maintenance-free requirements.
As a fluorine-based paint, an aqueous paint comprising water and a fluorine-containing polymer containing a unit based on a fluoroolefin and a unit based on a monomer having a crosslinkable group is known (Patent Document 1).

JP, 2009-046689, A

The present inventors apply the aqueous paint described in Patent Document 1 on a substrate to form a coating film, and as a result of evaluating the coating film, the coating film has low temperature conditions (0 ° C. or less). Although it is excellent in appearance, it has been found that there is room for improvement in its growth.
An object of the present invention is to provide a water-based paint capable of forming a coating film excellent in elongation under low temperature conditions.

  Therefore, as a result of intensive investigations, the present inventors have found that the problem can be solved by the following configuration.

[1] A unit based on a monomer having no crosslinkable group, which is at least one selected from the group consisting of units based on fluoroolefins, vinyl ethers, vinyl esters, allyl ethers, allyl esters and (meth) acrylic acid esters And a first polymer comprising a unit based on a monomer having a crosslinkable group, a fluoropolymer comprising a unit based on vinylidene fluoride and a unit based on hexafluoropropylene, a unit based on tetrafluoroethylene and propylene And a second polymer selected from the group consisting of a fluorine-containing polymer containing units based on the following, and a fluorine-containing polymer containing units based on the tetrafluoroethylene and a unit based on the perfluoroalkyl vinyl ether, and an anionic surfactant , Water, and containing Water-based paint.
[2] The water-based paint according to [1], wherein the content weight ratio of the content of the second polymer to the content of the first polymer in the water-based paint is 0.050 to 0.25.
[3] The water-based paint according to [1] or [2], wherein the total content of the first polymer and the second polymer is 60% by mass or more based on the total solid content of the water-based paint Water-based paint.
[4] The water-based paint according to any one of [1] to [3], wherein the second polymer is a fluorine-containing polymer containing a unit based on tetrafluoroethylene and a unit based on propylene.
[5] The aqueous paint according to any one of [1] to [4], wherein the content of the anionic surfactant is 0.001 to 0.1% by mass with respect to the total mass of the aqueous paint.
[6] The aqueous paint according to any one of [1] to [5] is coated on the surface of a substrate to form a coated layer, and the coated layer is dried to form a coated film. Method of producing a substrate
[7] A coated substrate having a substrate and a coating film formed of the water-based paint according to any one of [1] to [5] disposed on the surface of the substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the water-based paint which can form the coating film which is excellent in the elongation in low temperature conditions can be provided. The present invention can also provide a method for producing a coated film base having a coated film excellent in elongation under low temperature conditions, and a coated film base having the coated film on the surface of the substrate.

The meanings of the terms in the present specification are as follows.
The “unit” is a generic name of an atomic group directly formed by polymerization of a monomer and an atomic group obtained by chemical conversion of part of the atomic group formed by polymerization of a monomer. The content (mol%) of each unit relative to the total units contained in the polymer is determined by analyzing the polymer by nuclear magnetic resonance spectroscopy, and the charge of each monomer in the production of the polymer It can also be determined from
The numerical range represented using "-" means the range which includes the numerical value described before and after "-" as a lower limit and an upper limit.
"(Meth) acrylic" is a generic term for "acrylic" and "methacrylic".
The “average particle size of particles” is a volume average from a particle size distribution measured using a known particle size distribution measuring apparatus (Sympatec Co., Ltd., trade name “Helos-Rodos”, etc.) using a laser diffraction method as a measurement principle. It is a value obtained by calculation.
The "number average molecular weight" is a value measured by gel permeation chromatography using polystyrene as a standard substance. The "number average molecular weight" is also referred to as "Mn".
"Acid value" and "hydroxy value" are values measured according to the method of JIS K 0070-3 (1992), respectively.

The water-based paint of the present invention comprises a first polymer, a second polymer, an anionic surfactant, and water.
The first polymer is a unit based on fluoroolefin (hereinafter also referred to as “monomer F”) (hereinafter also referred to as “unit F”), vinyl ether, vinyl ester, allyl ether, allyl ester and (meth) It is at least one selected from the group consisting of acrylic esters, and is also referred to as a unit (hereinafter referred to as “unit 1”) based on a monomer having no crosslinkable group (hereinafter also referred to as “monomer 1”). And a fluorine-containing polymer containing a unit based on a monomer having a crosslinkable group (hereinafter also referred to as “monomer 2”) (hereinafter also referred to as “unit 2”).
The second polymer is a fluoropolymer including a unit based on vinylidene fluoride (hereinafter also referred to as “unit V”) and a unit based on hexafluoropropylene (hereinafter also referred to as “unit H”), tetrafluoro A fluoropolymer containing a unit based on ethylene (hereinafter also referred to as “unit T”) and a unit based on propylene (hereinafter also referred to as “unit P”), and a unit based on unit T and perfluoroalkylvinylether ( Hereinafter, it is a fluorine-containing polymer selected from the group which consists of a fluorine-containing polymer containing "the unit PF."
In addition, the coating film formed from the water-based coating material of this invention is also called "this coating film" hereafter.

The water-based paint of the present invention can form a coating excellent in elongation under low temperature conditions. The reason for this is not necessarily clear, but can be considered as follows.
In the water-based paint of the present invention, the first polymer which contributes to the weather resistance of the coating film and the adhesion to the substrate and the second polymer which contributes to the elongation of the film under low temperature conditions are dispersed in the form of particles. It is believed that the present coating is formed by the packing of the particles of the first polymer and the particles of the second polymer.
Due to the combination of the first polymer and the second polymer in the present invention and the dispersing effect of the particles by the contained anionic surfactant, the particles of the first polymer and the second polymer in the water-based paint of the present invention It is believed that the particles are highly uniformly dispersed. As a result, the packing of each particle proceeds densely, and a coating film with high uniformity of the distribution of the first polymer and the second polymer can be obtained. Therefore, the present coating film is excellent in elongation under low temperature conditions.

The monomer F is an olefin in which at least one hydrogen atom is substituted by a fluorine atom. In the fluoroolefin, one or more hydrogen atoms which are not substituted by a fluorine atom may be substituted by a chlorine atom.
Specific examples of fluoroolefins include tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene and vinylidene fluoride. The fluoroolefins may be used alone or in combination of two or more.
The content of the unit F is preferably 20 to 70 mol%, and more preferably 40 to 60 mol% with respect to all units contained in the first polymer, from the viewpoint of the weather resistance of the present coating film.

The monomer 1 is preferably a monomer represented by the formula X ¹² -Z ¹² .
X ¹² _{is, CH 2 = CHO-, CH 2} = CHCH 2 O-, CH 2 = CHOC (O) -, _{or, CH 2 = CHCH 2 OC (} O) - and is, in view of weather resistance of the coating film From the above, CH ₂ CHOCHO— or CH ₂ CHOCHOC (O) — is preferable.

Z ¹² is an alkyl group having 1 to 24 carbon atoms, and among them, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 6 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or 7 to 7 carbon atoms 12 aralkyl groups are preferred.
The alkyl group having 1 to 12 carbon atoms may be a linear alkyl group or a branched alkyl group. Moreover, a C1-C12 alkyl group may contain ring structure.

As a C1-C12 alkyl group, a methyl group, an ethyl group, a tert- butyl group, 2-ethylhexyl group, neononyl group, or a neodecanyl group is preferable.
As a C6-C10 cycloalkyl group, a cyclohexyl group is preferable.
As a C6-C10 cycloalkyl alkyl group, a cyclohexylmethyl group is preferable.
As a C7-C12 aralkyl group, a benzyl group is preferable.
As a C6-C10 aryl group, a phenyl group or a naphthyl group is preferable, and a phenyl group is more preferable.
The hydrogen atom of the cycloalkyl group, cycloalkylalkyl group, aryl group or aralkyl group may be substituted by an alkyl group. In this case, the carbon number of the alkyl group as a substituent is not included in the carbon number of the cycloalkyl group or the aryl group.
Specific examples of monomer 1 include ethyl vinyl ether, tert-butyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, vinyl acetate, vinyl pivalate, vinyl vinyl neononanoic acid (trade name "Beova 9" manufactured by HEXION) And neodecanoic acid vinyl ester (manufactured by HEXION, trade name “Beova 10”), benzoic acid vinyl ester, and tert-butyl (meth) acrylate.
The monomer 1 may be used alone or in combination of two or more.

  1-50 mol% is preferable with respect to all the units which a 1st polymer contains, and, as for content of the unit 1, 25-40 mol% is more preferable.

The crosslinkable group in the monomer 2 is preferably a hydroxy group or a carboxy group from the viewpoint of improving the coating strength of the present coating film as a crosslinking point.
That is, when the first polymer contains a unit based on a monomer having a hydroxy group as a crosslinkable group (hereinafter, also referred to as "monomer 21"), an isocyanate-based curing agent is included in the aqueous coating as a curing agent. If this is done, the coating strength of the present coating is further improved.
Moreover, when the first polymer contains a unit based on a monomer having a carboxy group as a crosslinkable group (hereinafter, also referred to as “monomer 22”), a carbodiimide curing agent, an amine curing agent, an oxazoline curing agent When the curing agent or the epoxy curing agent is included in the aqueous coating, the coating strength of the present coating is further improved. In particular, the curing agent used in the case of containing the above unit can improve the coating strength of the present coating film under low temperature conditions as compared with the case of using an isocyanate-based curing agent.

The monomer 21 is preferably a monomer represented by the formula X ²¹ -Z ²¹ or allyl alcohol.
X ²¹ is CH ₂ CHOCHO— or CH ₂ CHCHCH ₂ O—.
Z ²¹ is a C 2 -C 42 monovalent organic group having a hydroxy group. The group may be linear or branched. Also, the group may consist of a ring structure or may contain a ring structure.
As the group, an alkyl group having 2 to 6 carbon atoms, an alkyl group containing a cycloalkylene group having 6 to 8 carbon atoms, or a polyoxyalkylene group having a hydroxy group is preferable.
Specific examples of the monomer _{21, CH 2 = CHOCH 2 -cycloC} 6 H 10 -CH 2 OH, CH 2 = CHCH 2 O-CH 2 -cycloC 6 H 10 -CH 2 OH, CH 2 = CHOCH ₂ CH ₂ OH, CH ₂ CHCHCH ₂ OCH ₂ CH ₂ OH, CH ₂ CHO CHOCH ₂ CH ₂ CH ₂ CH ₂ OH, CH ₂ CHCHCH ₂ OCH ₂ CH ₂ CH ₂ CH ₂ OH, CH ₂ CHO CHOCH ₂ − _{cycloC 6 H 10 -CH 2 O (} CH 2 CH 2 O) 15 H , and the like. Incidentally, "- cycloC ₆ H ₁₀ -" represents _{cyclohexylene, (- cycloC 6 H 10 -} ) binding site is not particularly limited, is usually 1,4.
The monomers 21 may be used alone or in combination of two or more.

The monomer 22 is preferably a monomer represented by the formula X ²² -Z ²² .
X ²² _{is, CH 2 = CH-, CH (} CH 3) = CH-, _{or, CH 2 = C (CH 3} ) - and _is, CH 2 = _CH-, or, _{CH (CH} 3) = CH- is preferable.
Z ²² is a carboxy group or a monovalent C 1 to C 12 saturated hydrocarbon group having a carboxy group, preferably a carboxy group or a C 1 to C 10 carboxyalkyl group.
Specific examples of the monomer 22 include compounds represented by CH ₂ CHCHCOOH, CH (CH ₃ ) = CHCOOH, CH ₂ CC (CH ₃ ) COOH, and a formula CH ₂ CHCH (CH ₂ ) _{n 2} COOH ( However, n2 shows the integer of 1-10.) Is mentioned.
The monomers 22 may be used alone or in combination of two or more.

As the monomer 2, only one of the monomer 21 and the monomer 22 may be used, or both may be used.
The content of the unit 2 is preferably 1 to 20 mol%, more preferably 5 to 15 mol%, based on all units contained in the first polymer.

  From a viewpoint which is excellent in the softness | flexibility of this coating film, 30000-200000 are preferable and, as for Mn of a 1st polymer, 50000-180000 are more preferable.

  From the viewpoint of the film forming property of the present coating film, the content of the unit F, the content of the unit 1, and the content of the unit 2 of the first polymer are in this order relative to all units contained in the first polymer. 20 to 70 mol%, 1 to 50 mol%, and 1 to 20 mol% are preferable.

The second polymer includes a fluorine-containing polymer containing unit V and unit H (hereinafter also referred to as “polymer 21”), a fluorine-containing polymer containing unit T and unit P (hereinafter also referred to as “polymer 22”) And a fluorine-containing polymer selected from the group consisting of a fluorine-containing polymer (hereinafter also referred to as "polymer 23") containing unit T and unit PF.
In the present specification, the polymer 21, the polymer 22, and the polymer 23 correspond to the second polymer, respectively, and do not correspond to the first polymer.

  From the viewpoint of flexibility of the present coating film, Mn of the second polymer is preferably 10000 to 1000000, more preferably 20000 to 500,000 and particularly preferably 50000 to 300,000.

In the polymer 21, the content of the unit V and the unit H is preferably 1 to 95 mol% and 5 to 99 mol% in this order with respect to all units contained in the polymer 21, and 20 to 80 mol %, 20 to 80 mol% is more preferable.
The content of the unit T and the unit P in the polymer 22 is preferably 30 to 80 mol% and 20 to 70 mol% in this order with respect to all units contained in the polymer 22, and is preferably 40 to 70 mol. %, 60 to 30 mol% is more preferable.
In the polymer 23, the content of the unit T and the unit PF is preferably 30 to 70 mol% and 70 to 30 mol% in this order with respect to all units contained in the polymer 23, and 40 to 60 mol %, 70 to 30 mol% is more preferable.
Specific examples of the monomer 3 include perfluoromethyl vinyl ether, perfluoroethyl vinyl ether and perfluoropropyl vinyl ether.
In addition, as for the second polymer, the polymer 22 is preferable from the viewpoint of dispersion stability in water.

  The second polymer may contain units other than unit V, unit H, unit T, unit P, and unit PF. Specific examples of the unit include units based on ethylene, units based on 1,2-difluoroethylene, units based on 3,3,3-trifluoro-1-propene, based on 1,1,2-trifluoroethylene The unit includes a unit based on 1,3,3,3-tetrafluoropropene and a unit based on vinyl fluoride.

  Examples of the method for producing the first polymer and the second polymer include a method of copolymerizing each monomer in the presence of a solvent and a radical polymerization initiator. Specific examples of the polymerization method in the method of producing the first polymer and the second polymer include an emulsion polymerization method, a solution polymerization method, a suspension polymerization method, and a bulk polymerization method, and the emulsion polymerization method is preferable.

  The first polymer and the second polymer are preferably dispersed in water in the form of particles. The solution in which the polymer is dispersed in water is also referred to as an aqueous dispersion of the polymer.

The water-based paint of the present invention contains an anionic surfactant. The anionic surfactant is preferably a non-fluorinated anionic surfactant from the viewpoint of the storage stability of the aqueous coating and the water resistance of the present coating film.
In the present specification, the non-fluorinated anionic surfactant is a fluorine atom having an amphiphilic surfactant activity that contains a hydrophilic group (site) and an lipophilic group (site) in one molecule. It is a compound which is not contained and means a compound which dissociates in water to form an anion.
Specific examples of non-fluorinated anionic surfactants include fatty acid based anionic surfactants, linear alkylbenzene based anionic surfactants, higher alcohol based anionic surfactants, α-olefin based anionic surfactants And normal paraffinic anionic surfactants. More specific examples include sodium lauryl sulfate, sodium dodecyl benzene sulfonate, sodium alkyl sulfonate, sodium alkyl benzene sulfonate, sodium succinic acid dialkyl ester sulfonate, and sodium alkyl diphenyl ether disulfonate.

From the viewpoint of dispersion stability of the first polymer and the second polymer in water, the content of the anionic surfactant in the water-based paint of the present invention is 0.01 to the total mass of the first polymer. 15 mass% is preferable, and 0.1-10 mass% is more preferable.
An anionic surfactant may be added when producing the first polymer, or may be added when producing the second polymer, and when mixing the first polymer and the second polymer. However, from the viewpoint of the polymerizability of the first polymer, it is preferable to add it when producing the first polymer.

  Water in the present invention is a dispersion medium for dispersing the first polymer and the second polymer in an aqueous paint. The dispersion medium is made of only water or a mixed solvent of water and a water-soluble organic solvent. In the latter case, the content of the water-soluble organic solvent is preferably 5% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less, based on the total mass of water. Specific examples of the water-soluble organic solvent include methanol, ethanol, butanol, acetone and methyl ethyl ketone.

The content of the first polymer in the water-based paint of the present invention is preferably 30 to 80% by mass, more preferably 50 to 80% by mass, based on the total solid content of the water-based paint from the viewpoint of substrate adhesion of the coating film. More preferable.
From the viewpoint of the flexibility of the present coating, the content of the second polymer in the water-based paint of the present invention is preferably more than 0% by mass and 20% by mass or less, and 2-10% by mass with respect to the total solid content of the water-based paint. Is more preferred.
The total content of the first polymer and the second polymer in the water-based paint of the present invention is preferably 40% by mass or more, more preferably 50% by mass or more, and more preferably 55% by mass or more based on the total solid content of the water-based paint. Is more preferable, and 60% by mass or more is particularly preferable.
The content of the anionic surfactant in the water-based paint of the present invention is 0.001 to 0.1 based on the total weight of the water-based paint from the viewpoint of the dispersion stability of the first polymer and the second polymer in water. % By mass is preferable, and 0.01 to 0.5% by mass is more preferable.
The content of water in the water-based paint of the present invention is preferably 10 to 90% by mass, more preferably 40 to 60% by mass, with respect to the total mass of the water-based paint, from the viewpoint of storage stability and application efficiency of the water-based paint.
The content weight ratio of the content of the second polymer to the content of the first polymer in the water-based paint is preferably 0.050 or more from the viewpoint of the flexibility of the present coating, and the surface smoothness of the present coating From the viewpoint, 0.25 or less is preferable, and 0.17 or less is more preferable.

  The water-based paint of the present invention may optionally contain a first polymer, a second polymer, an anionic surfactant, and a component other than water (hereinafter, also referred to as an "additive"). Specific examples of the additive include polymers other than the first polymer and the second polymer, surfactants other than anionic surfactants, curing agents, pigments, dispersants, antifoaming agents, film-forming assistants, These include leveling agents, thickeners, curing aids, light stabilizers, ultraviolet light absorbers, and surface conditioners.

The water-based paint of the present invention may be applied directly to the surface of a substrate, or may be applied to the surface of a surface-treated (pretreated, etc.) substrate, or a resin layer (polyester resin layer, acrylic resin) on the surface You may apply | coat to the surface of the base material in which the layer, the epoxy resin layer, the urethane resin layer etc. were formed.
20-1000 micrometers is preferable, as for the film thickness of this coating film, from a durable viewpoint of this coating film, 20-500 micrometers is more preferable, and 25-150 micrometers is especially preferable.
Specific examples of the base material include non-metallic materials (resin, rubber, adhesive, organic materials such as wood, concrete, glass, ceramics, inorganic materials such as stone, etc.), metal materials (iron, iron alloys, etc.) Aluminum, aluminum alloy, copper, brass, titanium and the like can be mentioned.
As a specific example of the coating method of the water-based paint of this invention, the method of using coating apparatuses, such as a brush, a roller, dipping, a spray, a roll coater, a die coater, an applicator, a spin coater, is mentioned.

The present coating film is preferably obtained by applying the aqueous paint of the present invention to form a coated layer, and drying the coated layer to form a coated film. It is preferable to heat at the time of drying after application, and a heating temperature is preferably 25 ° C to 200 ° C.
That is, according to the present invention, the method of producing a coated film-coated substrate, wherein the aqueous paint of the present invention is applied on the surface of a substrate to form a coated layer, and the coated layer is dried to form a coated film. Is provided.
The coated substrate has the substrate and the coated film disposed on the surface of the substrate, and the coated film is hard to be broken even during bending under low temperature conditions and is excellent in flexibility. And can be suitably used in applications where elongation of the coating is required.

  Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to these examples. In addition, the compounding quantity of each component in the table | surface mentioned later shows a mass reference | standard.

[Component of aqueous dispersion containing first polymer]
Unit F: chlorotrifluoroethylene (CTFE)
Unit 1: Cyclohexyl vinyl ether (CHVE), 2-ethylhexyl vinyl ether (2-EHVE)
Unit 2: cyclohexanedimethanol monovinyl ether _{(CHMVE), CH 2 = CHOCH} 2 -cycloC 6 H 10 -CH 2 O (CH 2 CH 2 O) 15 H (CM-15EOVE)
Anionic surfactant 1: Sodium lauryl sulfate (SLS)
Nonionic surfactant 1: Polyoxyethylene alkyl ether (DKS NL-100 (trade name), manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

[Component of aqueous dispersion containing a second polymer]
Unit T: tetrafluoroethylene unit H: hexafluoropropylene unit V: vinylidene fluoride unit P: propylene

[Production Example 1 of Aqueous Dispersion]
CTFE (406 g), CHVE (291 g), 2-EHVE (161 g), CHMVE (24.8 g), CM-15 EOVE (14.5 g), ion-exchanged water (896 g), in a vacuum degassed autoclave equipped with a stirrer Potassium carbonate (1.4 g), nonionic surfactant 1 (44.8 g), and anionic surfactant 1 (0.89 g) were introduced and the temperature was raised and maintained at 50 ° C.
Subsequently, polymerization is carried out for 24 hours while continuously adding a 0.4% by mass aqueous solution of ammonium persulfate (50 mL) into the autoclave, and then the solution in the autoclave is filtered to obtain a fluoropolymer 1 as a first polymer. To obtain an aqueous dispersion 1 (fluorine-containing polymer concentration 52% by mass).
In addition, the fluoropolymer 1 is a unit based on CTFE, a unit based on CHVE, a unit based on 2-EHVE, a unit based on CHMVE, a unit based on CM-EOVE in this order 50 mol%, 33 mol%, 14 It was a polymer containing .75 mol%, 2 mol%, and 0.25 mol%.

[Production Example 2 of Aqueous Dispersion]
An aqueous dispersion 2 (fluorine-containing polymer concentration: 50% by mass) containing fluoropolymer 1 was obtained in the same manner as in Synthesis Example 1 except that the anionic surfactant was changed to 2.7 g.

[Production example 3 of aqueous dispersion]
An aqueous dispersion 3 containing fluoropolymer 1 (fluorine-containing polymer concentration: 47% by mass) was obtained in the same manner as in Synthesis Example 1 except that the anionic surfactant was changed to 0.010 g.

[Example 1]
Aqueous dispersion liquid 4 (fluorinated polymer concentration 34 containing the second polymer fluoropolymer 2 containing 56 mol% and 44 mol% unit T and unit P in this order in aqueous dispersion 1 (85 g) % By mass) (15 g) and a coalescent (CS-12, manufactured by Aldrich) (7.5 g) were added and mixed to obtain an aqueous paint 1. The water-based paint 1 was applied to the surface of the glass plate by an applicator so as to have a dry film thickness of 40 μm and dried at 25 ° C. for 2 weeks to obtain a coated glass plate formed from the water-based paint 1 . The coated film was peeled off from the coated glass plate and cut into 70 mm × 10 mm to obtain a coated film piece 1 which was subjected to the evaluation described later.

[Example 2, Example 3 and Example 7]
An aqueous paint and a coated film piece were obtained in the same manner as in Example 1 except that the mass of the aqueous dispersions 1 and 4 were changed as shown in Table 1, and subjected to the evaluation described later.

[Example 4]
An aqueous dispersion 5 (fluorinated polymer concentration containing a fluoropolymer 2 which is a second polymer, containing 55 mol% and 45 mol% of a unit V and a unit H in this order in the aqueous dispersion 1 (85 g) Coating piece 4 was obtained in the same manner as Example 1 except that 35% by mass) (15 g) and a film forming aid (7.5 g) were added and mixed to obtain an aqueous paint 4 and evaluations described later Provided for.

[Example 5 and Example 6]
An aqueous paint and a coated film piece were obtained in the same manner as in Example 1 except that the aqueous dispersion 1 was changed to the aqueous dispersion 2 or 3 as shown in Table 1, and subjected to the evaluation described later.

The evaluation method of the obtained water-based paint and a coating piece is shown below.
(Dispersion stability of water-based paint)
The dispersion stability of the water-based paints 1 to 7 was evaluated from the amount of precipitates generated during storage. Each 50 mL of the aqueous paint was placed in a centrifuge tube, allowed to stand at 25 ° C. for 2 weeks, and the amount of sediment settled at the bottom of the centrifuge tube was read from the scale.
○: The amount of precipitate is 0 to 0.1 mL.
Δ: The amount of precipitate is more than 0.1 mL and less than 0.5 mL.
X: The amount of precipitate is 0.5 mL or more.

(Appearance of coating film)
The appearance of the surface of the coated pieces 1 to 7 was visually evaluated.
○: The coated film surface of the coated piece was smooth.
Δ: The surface of the coated film was slightly wrinkled.
X: The surface of the coated film of the coated piece was wrinkled.

(Elongation of coating film)
About the coating film pieces 1-7, the point of 10 mm was each fixed in the center direction from the end of the two short sides which a coating film piece has. Then, the breaking elongation (%) at the time of applying a tensile load to a coating piece at 50 mm / min at -20 ° C from each point was measured. For measurement, ORIENTEC TENSILON RTC-1310A (manufactured by Orientec Co., Ltd.) was used.
○: Elongation at break of coating film pieces was 60% or more.
B: Elongation at break of the coated film piece was 20% or more and less than 60%.
X: Elongation at break of coating film piece was less than 20%.
The type of water-based paint used in each example and the evaluation results are shown in Table 1.
In addition, the number in the parenthesis in the compounding quantity of the water-based paint of Table 1 means the mass of the fluoropolymer contained in each water-based dispersion liquid.
Moreover, the polymer 2 / polymer 1 (mass reference | standard) of Table 1 represents content mass ratio of content of the polymer 2 with respect to content of the polymer 1 in water-based coating material.

  As shown in Table 1, the coating film of the aqueous coating containing the aqueous dispersions 1 to 3 containing the polymer 1 and the aqueous dispersions 4 to 5 containing the polymer 2 is excellent in elongation even at a low temperature.

Claims (7)

A unit based on a fluoroolefin-based unit, at least one member selected from the group consisting of vinyl ethers, vinyl esters, allyl ethers, allyl esters and (meth) acrylic acid esters and having no crosslinkable group, and A first polymer comprising units based on a monomer having a crosslinkable group,
Fluoropolymers comprising units based on vinylidene fluoride and units based on hexafluoropropylene, fluoropolymers comprising units based on tetrafluoroethylene and units based on propylene, and units based on tetrafluoroethylene and perfluoroalkylvinylethers A second polymer selected from the group consisting of fluorine-containing polymers containing units based on
An aqueous paint comprising an anionic surfactant and water.   The water-based paint according to claim 1, wherein the content weight ratio of the content of the second polymer to the content of the first polymer in the water-based paint is 0.050 to 0.25.   The total content of the first polymer and the second polymer in the water-based paint is 60% by mass or more based on the total solid content of the water-based paint. Water-based paint.   The water-based paint according to any one of claims 1 to 3, wherein the second polymer is a fluorine-containing polymer containing a tetrafluoroethylene-based unit and a propylene-based unit.   The water-based paint as described in any one of Claims 1-4 whose content of the said anionic surfactant is 0.001-0.1 mass% with respect to the total mass of the said water-based paint.   A coated substrate, wherein the aqueous paint according to any one of claims 1 to 5 is applied to the surface of a substrate to form a coated layer, and the coated layer is dried to form a coated film. Production method.   A coated substrate comprising: a substrate; and a coating formed of the water-based paint according to any one of claims 1 to 5 disposed on the surface of the substrate.